If you update to One UI 6, and factory reset, you will release a majority of the bugs you get from a drity flash, and your battery life will be wayyy better.
I recommend a backup of your things, or transfer to a PC all your goodies, then factory reset the phone if you’re having bad battery life, but I get almost 20 hours of Acreen On Time with my S918B/DS running Dr. Ketan
They just keep mashing the update button.